PURPOSE OF REVIEW: Allergic fungal sinusitis (AFS) results from an immunoglobulin E (IgE)-mediated, eosinophil-predominant hypersensitivity reaction to extramucosal fungi within the paranasal sinuses. Although the pathogenesis of this noninvasive process is still not fully understood, there is new information. Recently, the use of allergen immunotherapy with fungal antigens as an adjunct in treatment of AFS has been evaluated. In this review, we summarize the experience in the published literature on the topic.RECENT FINDINGS: There is evidence to suggest that allergen immunotherapy to fungal allergens may be effective in the treatment of symptoms of AFS and may decrease the rate of postoperative exacerbations and further operations. There is no evidence that this therapy induces immune complex disease. These studies pave the way for controlled trials of immunotherapy in patients with AFS.SUMMARY: Allergen immunotherapy to fungi shows promise as a treatment to decrease the recurrence of AFS and should be considered a part of the treatment regimen. However, because the number of patients treated has been small and one study suggested that fungal immunotherapy administered before removal of fungal contents from the sinuses could worsen sinusitis, controlled studies are essential to moving forward.